In the art a number of systems exists which makes it possible to arrange an X-ray source in a proper position in relation to an X-ray radiation receiver, e.g. a detector. Examples of such systems are described in U.S. Pat. No. 4,435,830 and EP 1306053. In both these systems the radiation source and the radiation receiver are mounted on separate extendable telescopic columns where the columns are arranged in carriages, which carriages are suspended from a rail system comprising rails in a first direction on which rails, the telescopic column carriage may slide and which rails are attached to rails arranged perpendicularly to the first rails, so that the first rails may slide in relation to the second set of rails. By being able to move the telescopic column basis along the first set of rails the relative distance between the telescopic columns and thereby between the radiation source and the radiation receiver may be varied. By further sliding the telescopic column carriages and the first set of rails in relation to the second set of rails it is possible to position the radiation source and radiation receiver in a variation of desired relative positions.
From U.S. Pat. No. 6,872,000 B2 a system is disclosed, which improves the manoeuvrability of the prior art systems by introducing a rotary device in the construction. This construction comprises a first set of rails mounted in a ceiling in a first direction and a second set of rails perpendicular to the first set of rails and which second set of rails may slide in the first direction. The rotary device is mounted under the second set of rails and may slide in the longitudinal direction of the second set of rails. To the lower side of the rotary device a further rail is mounted on which rail two telescopic columns may slide in the longitudinal direction of the rail. At the distal ends of the telescopic columns, an X-ray radiation source and an X-ray receiver are mounted.
Although this apparatus provides added user-friendliness and increased possibilities in order to position the radiation source and the radiation receiver, the positioning system has a number of drawbacks. One such drawback is the limitation in positioning flexibility caused by the fact that the two telescopic columns are sliding in the same rail. Hereby examinations, where oblique projections in both directions longitudinally along the table are to be performed, are not possible.
Often it is desirable to perform x-ray images at an oblique angle, i.e. different from vertical, where the oblique angle is obtained by displacing the two columns relative to each other in both directions in the longitudinal direction of the patient, and angle the source so that the radiation direction is towards the detector.
To do such examinations with the system disclosed in U.S. Pat. No. 6,872,000 B2, is not possible. To perform X-ray images at an oblique angle is only possible at the end of the table and only in one direction longitudinally of the patient. Hereby only very limited patient coverage is obtained, e.g. either head or feet and oblique angulation is only possible in one direction. This is impractical for examinations where oblique projections longitudinally to the patient are required other than head and feet, and in particular for examinations where oblique projections from both sides longitudinally along the whole patient or sections remote from the feet and head are required.
In addition the orientation of the source must also be variable, such that for some images it is desirable to have the image surface perpendicular to the radiation direction, and in other examinations it is desirable to orientate the image surface horizontally, i.e. parallel to the patient to be examined. Usually such examinations are carried out from varying angles in order to examine the organ or body part as thoroughly as possible.
To do such examinations with the system disclosed in U.S. Pat. No. 6,872,000 B2, is not possible other than at the end of the table and only in one direction longitudinally of the patient. Hereby only very limited patient coverage is obtained, e.g. either head or feet and angulation of the detector is only possible in one direction. This is impractical for examinations where the image surface is desired to be perpendicular to the radiation direction.
In order to provide power, data and other control information to and from the radiation source and the radiation receiver it is necessary to provide cabling. Due to the extensive range of movement in the first and second sets of rails in the case of a system according to U.S. Pat. No. 6,872,000 B2, it is necessary to provide cabling, so that the cables will be long enough in order to accommodate the devices in the most extreme positions. That in turn implies that when the radiation source and radiation receiver are close together and the moving parts overall are close together, the cabling will be slack and have a tendency to hang or be curled in bundles. These bundles furthermore may become entangled in the moving parts of the device or require special installations in order to collect the surplus cabling in a manner where it does not interfere with the proper working of the device. Furthermore, excess cabling may also be a source of dust or dirt collection which is not very desirable in a surgery or medical environment.